1. Field of the Invention
The invention relates to a technique for improving character readability when generating an image in which characters are disposed on an image such as a photograph.
2. Description of the Related Art
In documents such as catalogs and pamphlets, characters are often arranged with a photograph or the like as background. However, when characters are simply disposed on a background image, problems of character readability caused by the background photograph often arise. Techniques for improving the readability of characters disposed on a background image are described in JP-A-H5-257439, JP-A-200089747, and JP-A-H10-293835, for example. JP-A-H5-257439 and JP-A-2000-89747 disclose techniques for when characters are combined with a background image that involve detecting the color information of a peripheral portion of the characters, determining an opposite color based on the detected color information and the color information of the background image, and changing the color of the peripheral portion of the characters using the determined opposite color. JP-A-H10-293835 discloses a technique that involves adjusting the color values of the three-primary color data constituting a character image relative to the color values of the three-primary color data constituting the background image.
The above patent publications all involve changing only the color of the background image or the color of the character area. Consequently, if a background area overlapping with a character area had a high frequency characteristics, for example, character readability could not be sufficiently ensured due to background image flicker.